1. Field of the Invention
The present invention relates to flight instrument displays, particularly such displays for light aircraft and helicopters, and is of particular value in such aircraft having single pilots and no auto-pilot.
2. Discussion of Prior Art
It is well known that aircraft pilots operating without automatic controls require visual references to maintain controlled flight. Under certain conditions, which are commonly met during normal operations, such as in moisture or dust clouds or similar low visibility, the visual reference has to be provided by instruments. Conditions where instruments must be used are known as instrument flight conditions (IFC). Physical or cognitive misconceptions, particularly in instrument flight conditions, may lead a pilot to an incorrect understanding of his aircraft's orientation, a condition known as spatial disorientation (SD). Studies have shown that between 80-100% of aircrew, fixed wing and helicopter, have suffered SD to some degree. Studies have also shown that SD is a cause of many accidents, for example, it has been reported as a major factor in 32% of military helicopter accidents.
It is an important consideration that instrument displays should be easy to read and that readings from various instruments should be easily correlated to give the pilot a true picture of his aircraft's flight path. This is particularly important for conditions where an aircraft suddenly and unexpectedly enters poor visibility and the pilot has to make a rapid transition from visual to instrument flight conditions.
There is a need, therefore, for a simplified instrument display which provides an adequate source of information for standard instrument flight and which also provides an easy source of information for maintenance or re-establishment of a correct flight path on an occurrence of SD.